As everyone has stated, it's purely a matter of personal preference. If you are someone who is extremely averse to dealing with difficult situations, then getting a PM is a good idea. If you are someone who is willing to deal with difficult situations once in a blue moon, I personally feel it isn't worth it to get a PM.
@Michele Fischer mentioned getting a PM for finding new tenants, but you don't need a PM for this. You can either hire a real estate agent to market, show, and screen tenants for you (usually for 50% of the first month's rent), or just use something like RentPrep to do all credit and background checks and host an open house or two during the weekends. You can pay them an extra $12 for them to follow up on any tenant references.
I view PMs as a way that I can scale my business. Right now I have enough time where I can spare 1-2 hours a month with maintenance issues, calling contractors, and doing my accounting. When I start lacking free time, I'll start delegating to PMs. Once your property is up and running, it really should only be taking 1-2 hours of your time per month on average.
I highly encourage you to simply manage yourself because it gives you lots of excellent experience you'll need if/when you scale your investing larger. It'll save you tons of money too. If you find something taking too much of your time, delegate it, hire it out.
This doesn't happen very often. As long as you know some basics: where is the water main shut off, where is the main circuit breaker, where is the fire extinguisher, you should be okay. Get the number of a handyman willing to field emergency 24/7 calls just in case. If your house is on fire or any serious water related thing is happening, call the fire department. Anything that is not life threatening or property destroying can wait until the morning.
My biggest worry is that there is something that I am negligent about as a landlord simply because I am a new landlord. Laws/regulations that I did not know about specific to my state/county/city (I live in Hickory, NC). I think maybe a property management company, may already have systems in place and have more up-to-date info related to rentals that I may not be privy to.
You can hire a real estate attorney to draft all contracts that you have that are specific to your jurisdiction. The leases should be specific and comprehensive enough that if you ever have a question on what you can and cannot do, you just read the lease and it will tell you. If not, call the attorney and ask. Don't need a PM for this. The big thing that screws landlords in my area is not paying the tenant interest on security deposits. Attorneys can tell you all of this. You can also hire attorneys to do the entire eviction process for you, including posting all notices in the correct timeframe and showing up to court to plead your case.
So overall, you should view PMs as people who give you back free time, not necessarily someone who will expertly handle your property (because in many cases, they won't). If 1-2 hours a month of your time is worth 10% of your rent plus all additional related fees, you should do it. Otherwise, don't.